A user may be exposed to measurable radiofrequency electromagnetic radiation because of the radio waves emitted from the wireless communication device used for communicating. When conducting a conversation with a mobile communication terminal such as a mobile phone for instance, usually a user keeps his or her head within the electromagnetic radiation field emitted by the mobile phone. Therefore, governments of all countries including China have formulated comprehensive and safe standards and regulations to manage and restrain the exposure issues of radiofrequency energy; SAR (Specific Absorption Rate), which means electromagnetic wave adsorption rate and represents electromagnetic wave energy absorption rate of a mobile phone or other wireless communication devices, is an important evaluation parameter. It may be a test to indicate whether radiation impact from the mobile phone on the human body, especially the head, is in accordance with the standards. It is also a unit to show the amount of radiofrequency energy that may be absorbed by a human body using a mobile terminal, and may be used as a standard to protect the human body.
Currently, mobile terminals may be designed to be used under these extremely strict restrictions, so various devices and methods to lower SAR are under development. For example, design methods may include adding materials that can absorb an electromagnetic wave on a mobile terminal, optimizing radiofrequency induction current by the arrangement of metal parts, and complicated antenna design to lower SAR. However, these design methods may be often subject to the type of mobile terminals and may not be universally applicable.